Archive for the 'Optics basics' category

As I've mentioned a number of times before, my optics specialty is physical optics, which is the study of the wave properties of light. In order to understand those wave properties, however, it is important to understand what a 'wave' is and what it can do. This article is an attempt to answer these questions in a non-technical way for the layperson.

This is not as easy to do as one might think. Most of us are aware of numerous wave phenomena: waves on a string (such as a guitar string), water waves, sound waves (acoustical waves), seismic waves (earthquakes), 'The Wave' at football games. There are also many less familiar examples: light waves, particle waves (quantum mechanics), gravitational waves (caused by collapsing stars, for instance). It is quite difficult, however, to explain what these phenomena have in common. Furthermore, as we will see, any definition of a 'wave' that we come up with will have exceptions. I suspect most physicists would give a definition of a wave that's similar to the Potter Stewart definition of hard-core pornography: "I know it when I see it." We will do the best we can, though, and note those exceptions as they arise.

Since this is supposed to be in large part a science-focused blog, I wanted to get started with some serious posts about scientific topics. Like most of the established science bloggers, I'll be mixing up posts which are on basic scientific concepts and posts which are on specific, technical, topics. This post will be one of the former.

My physics specialization and area of research is optical science. Though most people associate the word 'optics' with the engineering of lenses for eyeglasses, telescopes, and microscopes, in physics the term more broadly refers to the study of the behavior of light and its interactions with matter. The connection to eyeglasses and the like is not accidental, however: the development of various optical tools led scientists to study more closely the behavior of the light that those tools channeled.

Today, we may roughly group the study of optics into three broad subfields of study:

Geometrical optics, the study of light as rays

Physical optics, the study of light as waves

Quantum optics, the study of light as particles

Let's look at each of these subfields in turn, both historically and scientifically.